Performance Max Asset Groups and Search Themes: A Structuring Playbook for 2026

CH.01Asset groups vs. search themes: two levers, not one

Before you touch the interface, get the two definitions exactly right, because every structuring mistake downstream traces back to blurring them. An asset group is a creative-and-relevance container. Google's model reads the headlines, descriptions, images, videos, and the landing page inside it to predict which queries and placements your offer should serve against. A search theme is not creative at all; it is a serving-priority signal that tells Google a phrase you already know converts, so the system does not have to wait to learn it.

The reason this distinction matters is mechanical. Search themes have the same prioritization as your phrase match and broad match keywords in your Search campaigns, and your exclusions and negative keywords still apply to them. They are also optional and additive to the queries and placements Performance Max already predicts from your assets, feeds, and landing pages. So a search theme never replaces a good asset group; it accelerates one.

CH.02Map intent themes before you touch the interface

Asset groups should mirror coherent intent themes, not your internal org chart. Translate your product lines, services, audiences, and value propositions into themes a customer would recognize, then make a simple rule: one theme equals one candidate asset group, with no product or audience overlap living inside the same group. The moment two unrelated themes share a group, the model can no longer attribute which creative drove which query, and the reporting becomes unreadable.

• List each distinct offering the way a buyer would describe it, not the way your catalog names it.
• Collapse near-identical offerings into one theme so the group has enough volume to learn from.
• Keep audience and product separated; do not split one product across two groups by audience unless creative and landing pages truly differ.
• Write the candidate theme name down before opening Google Ads so the structure drives the build, not the other way around.

CH.03Decide how many asset groups (the consolidation rule)

Start with two to four thematic groups, not ten. The published ceiling is high: a campaign can hold up to 100 asset groups, and each asset group can carry up to 1,000 listing groups. But that ceiling is irrelevant to most advertisers, because conversion volume, not creativity, sets the real cap. A thin asset group starves of the conversion signal the model needs to optimize, so it never gets good, no matter how polished the creative is.

Our rule of thumb on live accounts is to consolidate before you split. If a group is not generating enough conversions on its own to optimize, merge it into a sibling theme rather than letting it limp along. Split only when a theme has both distinct creative and enough demand to stand alone.

If a theme is too distinct to fit any existing group but does not justify its own, that is your signal to consider a separate campaign or a different campaign type. We unpack that decision in the Demand Gen vs. Performance Max comparison, and for ecommerce specifically, a feed-only Performance Max structure is often the cleaner answer than another asset group.

CH.04Fill each asset group to spec

Once your themes are set, fill each group with distinct creative built for that theme alone. Google publishes hard limits per asset group, and you should aim to give the model breadth without forcing thin, off-theme assets just to hit a maximum.

CH.05Layer search themes to claim the phrase and broad priority tier

Now use search themes deliberately. You can add up to 50 search themes per asset group, raised from the previous limit of 25. The increase was first reported in early May 2025 and confirmed in Google's own September 2025 announcement, so treat the rollout as phased through 2025 rather than a single launch date. The point of the higher cap is not to fill all 50 slots; it is to give you room to claim more of the priority tier with unique, non-redundant phrases.

The serving logic is what makes this a lever rather than a keyword field. Search themes share priority with your phrase and broad match Search keywords, and they sit below exact match. If a user's query is identical to an exact match keyword in your Search campaign, the Search campaign is prioritized over Performance Max. That single rule is what protects your highest-intent terms.

• Add only unique themes; duplicating the same theme idea wastes a slot without adding reach.
• Do not duplicate the exact-match terms your Search campaigns already win; exact match in Search outranks PMax on identical queries.
• Use the slots to cover phrase and broad intent you want PMax, not Search, to claim.
• Remember exclusions and negative keywords still apply to search themes, so your guardrails carry over.

CH.06Build the guardrails (the controls Google added in 2025)

Structuring is only half the job; the other half is preventing Performance Max from cannibalizing the Search campaigns you have already tuned. Google's September 2025 update added the controls that make this practical: campaign-level negative keyword lists, the raise from 25 to 50 search themes, search terms reporting for all PMax campaigns and via the API, and device, age, and beta gender controls.

1. Apply campaign-level negative keyword listsUse them to block queries you want handled elsewhere and to stop PMax from drifting into terms your Search campaigns own.
2. Set brand exclusions where neededBrand exclusions for Performance Max apply to Search and Shopping inventory, are built as account-level brand lists, and include an option to allow Shopping ads on searches that mention excluded brands.
3. Use the new demographic controlsDevice and age controls are available; gender launched as a beta per Google's September 2025 announcement, so confirm current availability before relying on it.
4. Protect exact match in SearchKeep your highest-intent terms as exact match in Search campaigns; identical queries are prioritized to Search over PMax, which is your strongest anti-cannibalization guardrail.

The brand exclusion and channel reporting controls in detail, including the Shopping carve-out, are covered in our Performance Max transparency updates breakdown.

CH.07Read the right reports

With the structure live, the reporting tells you whether your themes were coherent enough to learn from. Two things changed in 2025 that make this easier: search terms reporting is now available for all Performance Max campaigns and through the API, and asset group reporting gives you per-group performance. But one reporting caveat trips up almost everyone the first time.

Read asset group reporting to confirm each theme is pulling its weight; if a group is starved of conversions, that is your consolidation signal from Step 3. Read the search terms report to see what queries each theme and asset group actually triggered, then feed the converting phrases back into your structure and the non-converting ones into your negative keyword lists.

CH.08A reference structuring blueprint

Here is the full sequence applied to a multi-line advertiser, the way we would map it in an account. Imagine a brand with three distinct offerings, each with its own creative and landing page, and one branded-defense need.

• Asset group A wraps the first offering as one intent theme, filled to spec with on-theme headlines, images, and video, plus up to 50 unique search themes covering its phrase and broad intent.
• Asset group B does the same for the second offering; if its conversion volume is thin after a learning window, it merges into A rather than limping along.
• Asset group C handles the third offering only if it clears the conversion threshold; if not, it becomes a candidate for a separate campaign or a different campaign type.
• Guardrails sit at the campaign and account level: negative keyword lists block overlap, brand exclusions protect branded queries, and exact-match Search keywords keep the highest-intent terms in Search.

The decision tree at every branch is the same: new asset group when a coherent theme has distinct creative and enough demand to learn from; consolidate when it does not; new campaign or campaign type when the theme is too distinct to share a group but cannot justify its own. For where PMax sits inside the wider account, see how to structure Google Ads for an ecommerce store, and for the strategic context behind the whole campaign type, start with the pillar overview, Performance Max in 2026.

Run that loop consistently and the campaign compounds: coherent themes learn faster, deliberate search themes claim the priority tier without waste, and disciplined guardrails keep Performance Max and Search out of each other's way.